Less than 30K budget? PS3.
More than 40K budget? PC.
Reasons for PC:
*You can use Mouse and Keyboard in FPS games for added accuracy, and a gamepad too (in most games) if you like pads. (if you don't want official gamepad support, you can use Xpadder to use gamepads on any game you like).
*You can play at a smooth as hell 60 FPS setting. The games run like butter. They don't look sluggish.
*The graphical settings, the resolution, the Anti-Aliasing and the DX11, texture quality (which is usually 4 times that of consoles) features all provide mindblowing visuals. Just see the recent Crysis 3 trailer, or BF3 gameplay videos on PC to get an idea
Bazooka a wall to break it in pieces and make a new opening into the building. Why wait for Next Gen when you can have one now?
*There are plentiful games available. In the first half of the year, you get the usual multiplatform games and some quality indie games. In the middle to second half of the year, you get great exclusives + multiplats.
*Legit games are cheap on the PC, if you buy their key only. A person could get a $60 game for $30 if he buys the game's key only and downloads the stuff from a client/torrent.
*Mods on the PC add value to the game. Install mods on games like Skyrim to blow them to the limits.
*You have full control over your games. You can change the control scheme at will. You can add smoothness in a game, or add graphical quality to your liking. Remember gameplay is directly affected by how smooth a game runs.
Immersion is directly affected by the quality of the visuals. For me at least.